1. Field of the Invention
This invention relates to an information-code-image capturing apparatus. Also, this invention relates to an optical information reading apparatus. In addition, this invention relates to a system for setting an image input timing or an image capture timing.
2. Description of the Related Art
In general, an information-representing code such as a bar code or a two-dimensional code is provided on the surface of an article. A conventional apparatus for optically reading an information-representing code includes a light emitter, a CCD sensor, and a signal processor. The light emitter includes, for example, an LED. The light emitter applies forward reading light to the target surface of an article on which an information-representing code is provided. The CCD sensor includes, for example, an array of photosensors. The CCD sensor receives return light which results from reflection of the forward reading light at the target surface of the article. The return light represents an image of the information-representing code. The CCD sensor converts the return light into an electric signal representing the image of the information-representing code. In this way, an image of the information-representing code is captured or inputted. The signal processor decodes the electric signal to recover the information represented by the code.
There is a known apparatus for optically reading information-representing codes which are moving, for example, information-representing codes provided on articles which are being carried by a belt conveyor. The known apparatus includes a light emitter and a CCD sensor. The light emitter outputs forward reading light at a timing when an information-representing code on an article comes into the view of the CCD sensor.
Japanese published unexamined patent application 53-69538 discloses a system in which objects to be inspected are successively carried by a belt conveyor. In the system of Japanese application 53-69538, a position sensor detects whether or not an object comes into the view of a fixed television camera. When the position sensor detects that an object comes into the view of the television camera, a strobe device applies a flash of light to the object. Thus, the television camera outputs an electric signal representing a still image of the object which is substantially independent of the speed of movement of the object. The pattern of the object is recognized by referring to the still image of the object which is represented by the output signal of the television camera. In the system of Japanese application 53-69538, parallel mark lines are provided on the surface of the belt of the conveyor. The mark lines are covered by objects, and are exposed in the regions between the objects. Thus, the mark lines are separated into spaced segments as viewed from the television camera. In the processing of the output signal of the television camera, ends of segments of the mark lines are used as indications of starting edges of the patterns of the objects.
Japanese published unexamined patent application 61-133486 discloses a system in which objects having bar codes are successively carried by a belt conveyor. In the system of Japanese application 61-133486, a position sensor detects whether or not a bar code on an object comes into the view of a fixed camera. When the position sensor detects that a bar code on an object comes into the view of the camera, a strobe device applies a flash of light to the bar code. Thus, the camera outputs an electric signal representing a substantially still image of the bar code on the object. The output signal of the camera is decoded to recover the information represented by the bar code.
U.S. Pat. No. 5,698,833 discloses a method of determining the location and approximate orientation of a bar code on a substrate. The method in U.S. Pat. No. 5,698,833 is implemented by an omnidirectional bar-code locator. A digit image is a one-bit representation of a standard eight-bit grey scale video image produced by a CCD camera. The omnidirectional bar-code locator processes, in real-time, a digital video signal defining a pixelized image of a conveyor carrying parcels through the field of the view of the CCD camera. The omnidirectional bar-code locator divides the video image into a plurality of cells and produces two output signals, a cell bar-code indication signal and a cell bar-code orientation signal, for each cell. A host computer responds to a xe2x80x9ctruexe2x80x9d cell bar-code indication signal for a cell by storing the portion of the video image corresponding to the cell in a mass storage memory. The host computer also stores a representation of the cell bar-code orientation signal for each cell in which the cell bar-code indication signal is xe2x80x9ctruexe2x80x9d. The omnidirectional bar-code locator thus allows the host computer to store only those cells of the video image that contain bar-code data. The bar-code data may then be provided to a bar-code reader for further processing.
U.S. Pat. No. 5,698,833 also discloses that a belt encoder provides a signal indicating the linear displacement of a conveyor. The CCD camera is cycled in response to the signal from the belt encoder to generate a series of analog line images that are transmitted to a digitizer. The belt encoder triggers the CCD camera at a specified rate so that the resolution of the image created by the CCD camera is equal to a given number of pixels in the direction of the travel of the conveyor.
U.S. Pat. No. 5,754,670 corresponding to Japanese published unexamined patent application 9-6891 discloses a data symbol reader of a fixed type which includes a CCD camera. In the data symbol reader of U.S. Pat. No. 5,754,670, when a reading process is executed, a frame image capture is carried out by the CCD camera. Calculation is given of the number of pixels provided by the CCD camera which corresponds to the displacement or the difference between a first-field image and a second-field image. The speed of movement of a data symbol is computed on the basis of the calculated pixel number. An optimal light exposure time is calculated from the computed speed of movement of the data symbol. Then, an optimal intensity of illumination is calculated from the optimal light exposure time. Reading the data symbol is carried out under conditions using the optimal light exposure time and the optimal illumination intensity. In the data symbol reader of U.S. Pat. No. 5,754,670, the light exposure is optimally controlled in accordance with the speed of movement of the data symbol.
It is a first object of this invention to provide an improved information-code-image capturing apparatus.
It is a second object of this invention to provide an improved optical information reading apparatus.
It is a third object of this invention to provide an improved system for setting an image input timing or an image capture timing.
A first aspect of this invention provides an information-code-image capturing apparatus for emitting light toward an article moving along a carry path, and receiving reflected light and capturing an image of an information code on the article. The apparatus comprises detecting means for detecting that the article reaches a predetermined position in the carry path; image capturing means for capturing the image on the basis of the reflected light when a time interval has elapsed since a moment at which the detecting means detects that the article reaches the predetermined position; positional information calculating means for calculating positional information on the basis of the image captured by the image capturing means, the positional information enabling an area of the information code to be determined in the captured image; and capture timing correcting means for correcting the time interval on the basis of the positional information calculated by the positional information calculating means.
A second aspect of this invention is based on the first aspect thereof, and provides an information-code-image capturing apparatus wherein the positional information calculating means comprises means for calculating the positional information on the basis of a positioning symbol in the information code.
A third aspect of this invention is based on the second aspect thereof, and provides an information-code-image capturing apparatus wherein the positional information calculating means comprises means for calculating a position of a center of the information code as the positional information on the basis of the positioning symbol in the information code.
A fourth aspect of this invention is based on the second aspect thereof, and provides an information-code-image capturing apparatus wherein the information code comprises a QR code, and the positional information calculating means comprises means for calculating a position of a center of a positioning symbol in the QR code as the positional information.
A fifth aspect of this invention is based on the first aspect thereof, and provides an information-code-image capturing apparatus wherein the time interval comprises a plurality of different sub time intervals; the image capturing means comprises means for capturing an image when each of the sub time intervals has elapsed since the moment at which the detecting means detects that the article reaches the predetermined position; the positional information calculating means comprises means for calculating positional information for each of the images captured by the image capturing means; and the capture timing correcting means comprises means for correcting each of the sub time intervals on the basis of the positional information calculated by the positional information calculating means.
A sixth aspect of this invention is based on the fifth aspect thereof, and provides an information-code-image capturing apparatus wherein the capture timing correcting means comprises means for detecting a direction of carry of the article on the basis of the calculated positional information for each of the captured images, and means for correcting each of the sub time intervals in response to the detected direction of carry of the article.
A seventh aspect of this invention provides an optical information reading apparatus comprising an information-code-image capturing apparatus including the information-code-image capturing apparatus in one of the first to sixth aspects of this invention; and decoding means for executing a decoding process with respect to the information code in the image captured by the information-code-image capturing apparatus to read information represented by the information code.
An eighth aspect of this invention provides a system for setting an image capture timing. The system comprises an optical information reading apparatus for emitting light toward an article moving along a carry path, and receiving reflected light and capturing an image of an information code on the article; and an information processing apparatus being separate from the optical information reading apparatus and being able to implement data communications with the optical information reading apparatus;
wherein the optical information reading apparatus comprises 1) detecting means for detecting that the article reaches a predetermined position in the carry path; 2) image capturing means for capturing the image on the basis of the reflected light when a time interval has elapsed since a moment at which the detecting means detects that the article reaches the predetermined position; 3) transmitting means for transmitting the image captured by the image capturing means to the information processing apparatus; and 4) capture timing correcting means for receiving a correcting command from the information processing apparatus, and for correcting the time interval in response to the correcting command; and wherein the information processing apparatus comprises 1) positional information calculating means for calculating positional information on the basis of the image transmitted from the optical information reading apparatus; and 2) command generating means for generating the correcting command on the basis of the positional information calculated by the positional information calculating means, and for transmitting the correcting command to the optical information reading apparatus.
A ninth aspect of this invention provides an adaptive apparatus for capturing at least portions of images of successively carried articles having information-representing codes at equal positions of the articles. The apparatus comprises first means for detecting whether or not an article reaches a predetermined position; a fixed image sensor; second means for capturing at least a portion of an image of the article via the image sensor when a variable time interval has elapsed since a moment at which the first means detects that the article reaches the predetermined position; third means for detecting a position of an information-representing code in the image captured by the second means; and fourth means for varying the time interval in response to the position detected by the third means.